BBC and Masterpiece previously released a clip at Comic-Con, but this new trailer is sure to get you even more jazzed about the special.

"It's like we checked the books and discovered we'd set it in the wrong time period by mistake and it's like we're correcting it for 90 minutes," Steven Moffat, executive producer and co-creator, previously told BBC News. "We're really proud of it, we think it's a real cracker. But that'll be it until series four."